The present invention relates to surgical instruments and particularly to an improved seal arrangement for a trocar tube.
A conventional trocar assembly comprises two basic interfitting, separable components: a trocar obturator subassembly and a trocar tube subassembly. The trocar obturator subassembly includes a supporting head with an elongate obturator having a cutting tip and a protective shield. The trocar tube includes a head and a depending tube together with a sealing arrangement within the head for closing and sealing the tube when it is in position during surgery. The assembly includes the trocar obturator and protective shield interfitting the trocar tube with the cutting tip projecting from the end of the tube and being covered by the protective shield.
In ordinary use the trocar assembly penetrates a body cavity and the trocar obturator subassembly is withdrawn leaving the trocar tube in place for introducing other instruments into the body according to the requirements of a particular medical procedure. The trocar tube is provided with a sealing arrangement to close the tube in order to maintain the gas pressure within the body cavity as required for the medical procedure.
Conventional sealing arrangements such as disclosed in U.S. Pat. Nos. 4,931,042 and 5,030,206 include a swinging flapper valve located in the head portion of the trocar tube subassembly which swings closed when the obturator and protective shield are removed. The flapper valve is spring loaded and closes against a sealing ring or grommet fitted around the head access opening. When an instrument is inserted into the trocar tube the flapper valve is either pushed aside by the instrument or by an external lever fitted to the side of the head portion. The flapper valve arrangement although providing a suitable seal is a rather cumbersome arrangement.
U.S. Pat. No. 4,972,827 utilizes a slide valve fitted within a chamber forming part of the trocar tube. The slide valve and chamber are oriented perpendicular to the trocar tube axis and when the trocar obturator is removed, the slide valve is pushed laterally by a spring to cross over the tube axis and seal the tube. This arrangement is also cumbersome and requires manual operation to align the opening through the slide valve with the trocar obturator or other instrument required for a medical procedure.